• The Transactions of the Korean Institute of Electrical Engineers A
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• v.49 no.8
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• pp.418-423
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• 2000

In this paper, we reported the current limiting properties of superconducting fault current limiters (SFCL). Our SFCL was patterned in a coil-type on a YBCO film deposited using rf sputtering techniques and was coated with a gold shunt layer in order to disperse the heat generated at hot spots in the YBCO film. Current increased up to 13.5 Apeak at 60 Hz for the voltage of 11.5 Vpeak, which is the minimum quench point, and increased up to 17.6 Apeak at 60 Hz for the voltage of 80 Vpeak. The quench completion time was 5 msec at 11.5 Vpeak and 4 msec at 80 Vpeak respectively. We think that this architecture using coil-type SFCL can be useful for the protection of the power delivery systems from fault currents.

• Journal of the Microelectronics and Packaging Society
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• v.21 no.3
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• pp.63-66
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• 2014

In this study, we investigated the effects of Cu TSV on the thermal management of 3D stacked IC. Combination of backside point-heating and IR microscopic measurement of the front-side temperature showed evolution of hot spots in thin Si wafers, implying 3D stacked IC is vulnerable to thermal interference between stacked layers. Cu TSV was found to be an effective heat path, resulting in larger high temperature area in TSV wafer than bare Si wafer, and could be used as an efficient thermal via in the thermal management of 3D stacked IC.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.7 s.238
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• pp.921-929
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• 2005

This paper presents an accelerated life test for burnout of tungsten filament of incandescent lamp. From failure analyses of field samples, it is shown that their root causes are local heating or hot spots in the filament caused by tungsten evaporation and wire sag. Finite element analysis is performed to evaluate the effect of vibration and impact for burnout, but any points of stress concentration or structural weakness are not found in the sample. To estimate the burnout life of lamp, an accelerated life test is planned by using quality function deployment and fractional factorial design, where voltage, vibration, and temperature are selected as accelerating variables. We assumed that Weibull lifetime distribution and a generalized linear model of life-stress relationship hold through goodness of fit test and test for common shape parameter of the distribution. Using accelerated life testing software, we estimated the common shape parameter of Weibull distribution, life-stress relationship, and accelerating factor.

• Clinical and Experimental Pediatrics
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• v.59 no.sup1
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• pp.29-31
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• 2016

Glucose transport 1 (GLUT-1) deficiency is a rare syndrome caused by mutations in the glucose transporter 1 gene (SLC2A1) and is characterized by early-onset intractable epilepsy, delayed development, and movement disorder. De novo mutations and several hot spots in N34, G91, R126, R153, and R333 of exons 2, 3, 4, and 8 of SLC2A1 are associated with this condition. Seizures, one of the main clinical features of GLUT-1 deficiency, usually develop during infancy. Most patients experience brief and subtle myoclonic jerk and focal seizures that evolve into a mixture of different types of seizures, such as generalized tonic-clonic, absence, myoclonic, and complex partial seizures. Here, we describe the case of a patient with GLUT-1 deficiency who developed infantile spasms and showed delayed development at 6 months of age. She had intractable epilepsy despite receiving aggressive antiepileptic drug therapy, and underwent a metabolic workup. Cerebrospinal fluid (CSF) examination showed CSF-glucose-to-blood-glucose ratio of 0.38, with a normal lactate level. Bidirectional sequencing of SLC2A1 identified a missense mutation (c.1198C>T) at codon 400 (p.Arg400Cys) of exon 9.

• Journal of Powder Materials
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• v.21 no.6
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• pp.441-446
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• 2014

In this study, we synthesize silica-core gold-satellite nanoparticles (SGNPs) for the surface-enhanced Raman scattering (SERS) based sensing applications. They consist of gold satellite nanoparticles (AuNPs) fixed on the silica core nanoparticles, which sizes of AuNPs can be tunned by varying the amount of reactants (growth solution and reducing agent). Their surface plasmon resonance (SPR) properties were characterized by using UV-vis spectroscopy, showing that the growth of AuNPs on silica cores leads to the light absorption in the longer wavelength region. Furthermore, the size increase of AuNPs exhibited the dramatic change in SERS activity due to the formation of hot spots. The optimized SGNPs showing enhancement factor ${\sim}3.8{\times}10^6$ exhibited a detection limit of rhodamine 6G (R6G) as low as $10^{-8}M$. These findings suggest the importance of size control of SGNPs and their SPR properties to develop highly efficient SERS sensors.

• Korean Journal of Remote Sensing
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• v.28 no.6
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• pp.661-670
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• 2012

Urban forests provide great ecosystem services to population in metropolitan areas even though they occupy little green space in a huge gray landscape. Unfortunately, urbanization inherently results in threatening the green infrastructure, and the recent urbanization trends drew great attention of scientists and policy makers on how to preserve or restore green infrastructure in metropolitan area. For this reason, mapping the spatial distribution of the green infrastructure is important in urban environments since the resulting map helps us identify hot green spots and set up long term plan on how to preserve or restore green infrastructure in urban environments. As a preliminary step for mapping green infrastructure utilizing multi-source remote sensing data in urban environments, the objective of this study is to map vegetation volume by fusing LiDAR and multispectral data in urban environments. Multispectral imageries are used to identify the two dimensional distribution of green infrastructure, while LiDAR data are utilized to characterize the vertical structure of the identified green structure. Vegetation volume was calculated over the metropolitan Chicago city area, and the vegetation volume was summarized over 16 NLCD classes. The experimental results indicated that vegetation volume varies greatly even in the same land cover class, and traditional land cover map based above ground biomass estimation approach may introduce bias in the estimation results.

• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.3
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• pp.284-290
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• 2012

Infrared thermography uses infrared energy radiated from any objects above absolute zero temperature, and the range of its application has been constantly broadened. As one of the active test techniques detecting radiant energy generated when energy is applied to an object, ultrasound infrared thermography is a method of detecting defects through hot spots occurring at a defect area when 15~100 kHz of ultrasound is excited to an object. This technique is effective in detecting a wide range affected by ultrasound and vibration in real time. Especially, it is really effective when a defect area is minute. Therefore, this study conducted thermography through lock-in signal processing when an actual defect exists inside the austenite STS304 seamless pipe, which simulates thermal fatigue cracks in a nuclear power plant pipe. With ultrasound excited, this study could detect defects on the rear of a pipe by using an aluminium reflector. Besides, by regulating the angle of the aluminium reflector, this study could detect both front and rear defects as a single infrared thermography image.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.4
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• pp.324-329
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• 2010

Fuel rods using in nuclear power plants consist of uranium dioxide pellets enclosed in zirconium alloy(zircaloy) tubes. It is vitally important for the pellet surface to remain free from pits, cracks and chipping defects after it is loaded into the tubes to prevent local hot spots during reactor operation. This paper investigates the feasibility study for detecting surface flaws of pellets contained within nuclear fuel rod through X-ray tomography simulation. Reconstructed images used by parallel and fan-beam filtered back projection method were presented and confirmed the accessibility between simulation data and MPS(missing pellet surface) image data.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.11
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• pp.5264-5281
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• 2017

Multihop relay-based cellular networks are attracting much interest because of their throughput enhancement, coverage extension, and low infrastructure cost. In these networks, relay stations (RSs) between a base station (BS) and mobile stations (MSs) drastically increase the overall spectral efficiency, with improved channel quality for MSs located at the cell edge or in shadow areas, and enhanced throughput of MSs in hot spots. These relay-based networks require an advanced radio resource management scheme because the optimal amount of radio resource for a BS-to-RS link should be allocated according to the MS channel quality and distribution, considering the interference among RSs and neighbor BSs. In this paper, we propose optimal resource planning algorithms that maximize the overall utility of relay-based networks under a proportional fair scheduling policy. In the first phase, we determine an optimal scheduling policy for distributing BS-to-RS link resources to RSs. In the second phase, we determine the optimal amount of the BS-to-RS link resources using the results of the first phase. The proposed algorithms efficiently calculate the optimal amount of resource without exhaustive searches, and their accuracy is verified by comparison with simulation results, in which the algorithms show a perfect match with simulations.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.4
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• pp.437-450
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• 2004

Extensive forest fire activities occurred across the border in Russia, particularly east of Lake Baikal between the Amur and Lena rivers in May 2003. These forest fires released large amounts of particulates and gases into the atmosphere, resulting in adverse effects on regional air quality and the global radiation budget. Smoke pollution from the Russian fires near Lake Baikal was transported to Korea through Mongolia and eastern China. On 20 May 2003, a number of large fires were burning in eastern Russian, producing a thick, widespread pall of smoke over much of Northeast Asia. In this study, separation technique was used for aerosol retrieval application with imagery from MODIS aboard TERRA satellites. MODIS true-color image shows the location of fires and the grayish color of the smoke plumes over Northeast Asia. Aerosol optical thckness (AOT) retrieved from the MODIS data were compared with fire hot spots, ground-based radiation data and TOMS -based aerosol index data. Large AOT, 2.0-5.0 was observed on 20 May 2003 over Korea due to the influence of the long range transport of smoke aerosol plume from the Russian fires, while surface observed fine mode of aerosol size distribution increased.